BEHAVIOR AND FUNCTIONS OF THE NUCLEUS 307 



of the anlage proceeding slowly. In any case the single node was 

 able to support regeneration eventually, for increases in the nucleus 

 occurred only afterward (Fig. 86b). Occasionally no regeneration 

 occurred at all, although the single macronuclear node persisted 

 intact until death of the specimen. Therefore extreme reductions 

 show that the nucleo-cytoplasmic ratio does have an important 

 effect at least on the time required for oral regeneration. 



An interesting question is posed by what happens to the single 

 node which enables it to support primordium formation even in 

 a large mass of cytoplasm. For if all but one nuclear bead is removed 

 from a stentor in process of regeneration, I found that early 

 primordia were then resorbed, though later anlagen could run 

 their course of development with the support of the single remain- 

 ing node (unpublished). In a stentor with 15 nodes each may carry 

 only I /15th of the burden of supporting primordium formation 

 and development. For one node to do so, especially within a large 

 mass of cytoplasm, may require an adaptation in which the output 

 of this single node becomes greatly accelerated. 



There is some evidence that in stentors with greatly reduced 

 nuclear complement the general metabolism of the cell may be 

 upset until this disparity is redressed. The first hint of such effects 



B. Delayed primordium formation in hypernucleates. a: 

 When a sector with stage-2 regeneration anlage and one macro- 

 nuclear node was grafted to non- differentiating stentor minus 

 nucleus and mouthparts the primordium was promptly resorbed 

 and no regeneration occurred until 3 days later. No nuclear 

 increase occurs until after anlage passes through stage 6. b: A 

 fusion mass of 2 stentors coerideus with mouthparts and all but 2 

 nodes excised did not regenerate until two days later, the 2 nodes 

 increasing to 7 only as the anlagen completed development. 



C. Regeneration of the macronuclear chain and reconstitution 

 of proportionate parts, a: One macronuclear node in head 

 folded on itself, b: Shape regenerated and feeding organelles 

 reduced to proportionate size without primordium formation, 

 single node now spindle form (to increase its active surface 

 area?); reorganization primordium (to make possible nuclear 

 increase?), c: After reorganization the specimen has 9 small 

 nodes, d: Membranellar band and frontal field, again made 

 relatively too large through reorganization, are adaptively 

 decreased in size, e: Before its demise, the animal had 7 nodes 



(adaptation to decreasing size in starvation on the slide?). 



